Semiconductor constructions

ABSTRACT

The invention includes a method of depositing a noble metal. A substrate is provided. The substrate has a first region and a second region. The first and second regions are exposed to a mixture comprising a precursor of a noble metal and an oxidant. During the exposure, a layer containing the noble metal is selectively deposited onto the first region relative to the second region. In particular applications, the first region can comprise borophosphosilicate glass, and the second region can comprise either aluminum oxide or doped non-oxidized silicon. The invention also includes capacitor constructions and methods of forming capacitor constructions.

TECHNICAL FIELD

The invention pertains to methods of depositing noble metals. Theinvention also pertains to methods of forming capacitor constructions,as well as to the capacitor constructions themselves.

BACKGROUND OF THE INVENTION

Capacitors are utilized in numerous semiconductor constructions,including, for example, dynamic random access memory (DRAM) devices.Capacitors comprise a pair of electrically conductive materials(frequently referred to as a storage node and a capacitor plate) whichare separated from one another by dielectric material. The conductivematerials are thus capacitively coupled with one another.

Various materials have been utilized for the conductive components ofcapacitor constructions, including, for example, metals, metalsilicides, metal nitrides and conductively-doped semiconductor materials(such as, for example, conductively-doped silicon). Materials that canbe particularly useful in capacitor constructions are so-called noblemetals, which include, for example, platinum, rhodium, iridium,palladium and ruthenium. A difficulty in utilizing the noble metals isin patterning constructions from the metals. For instance, if platinumis utilized to form a conductive component of a capacitor construction,it can be difficult to pattern the platinum into a desired shape.

One of the methods that is frequently utilized for patterning platinumis chemical-mechanical polishing. However, such method can smearplatinum. The smearing can cause undesirable defect structures.

It would be desirable to develop new methods of forming noble metalsinto desired shapes for semiconductor applications, and it would beparticularly desirable if such new methods could be applied tofabrication of capacitor structures.

Although the invention was motivated by the applications discussedabove, it is to be understood that the invention is not limited to suchapplications except to the extent that the applications are explicitlyrecited in the claims which follow.

SUMMARY OF THE INVENTION

In one aspect, the invention encompasses a method of depositing at leastone noble metal. A substrate is provided. The substrate includes firstand second materials, with the first material being different than thesecond material. The first and second materials are exposed to a mixturecomprising at least one precursor of at least one noble metal and atleast one oxidant. During the exposure to the mixture, a layercontaining at least one noble metal is selectively deposited onto thefirst material relative to the second material. In particularapplications, the first material can comprise borophosphosilicate glass,and the second material can comprise either aluminum oxide or dopednon-oxidized silicon.

In one aspect, the invention encompasses a method of forming a capacitorconstruction. A substrate is provided, and a first material is formedover the substrate. A second material is formed over the first material.Openings are formed to extend through the second material and into thefirst material. After the openings are formed, regions of the first andsecond materials are exposed to a mixture containing at least oneprecursor of at least one noble metal and at least one oxidant. A firstlayer comprising at least one noble metal is selectively deposited ontothe first material relative to the second material as the materials areexposed to the mixture. The first layer is then exposed to conditionswhich roughen it. An electrically conductive second layer is formed overthe roughened first layer, a dielectric third layer is formed over thesecond layer, and an electrically conductive fourth layer is formed overthe third layer.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention are described below withreference to the following accompanying drawings.

FIG. 1 is a diagrammatic, cross-sectional view of a semiconductor waferfragment at a preliminary processing stage of an exemplary aspect of thepresent invention.

FIG. 2 is a view of the FIG. 1 fragment shown at a processing stagesubsequent to that of FIG. 1.

FIG. 3 is a view of the FIG. 1 fragment shown at a processing stagesubsequent to that of FIG. 2.

FIG. 4 is a view of the FIG. 1 fragment shown at a processing stagesubsequent to that of FIG. 3.

FIG. 5 is a view of the FIG. 1 fragment shown at a processing stagesubsequent to that of FIG. 4.

FIG. 6 is a view of the FIG. 1 fragment shown at a processing stagesubsequent to that of FIG. 4 in accordance with an aspect of theinvention alternative to that described with reference to FIG. 5.

FIG. 7 is a view of the FIG. 1 fragment shown at a processing stagesubsequent to that of FIG. 4 in accordance with another aspect of theinvention.

FIG. 8 is a view of the FIG. 7 fragment shown at a processing stagesubsequent to that of FIG. 7.

FIG. 9 is a view of the FIG. 7 fragment shown at a processing stagesubsequent to that of FIG. 8.

FIG. 10 is a view of the FIG. 7 fragment shown at a processing stagesubsequent to that of FIG. 9.

FIG. 11 is a view of the FIG. 1 fragment shown at a processing stagesubsequent to that of FIG. 8 in accordance with yet another aspect ofthe invention.

FIG. 12 is a view of the FIG. 11 fragment shown at a processing stagesubsequent to that of FIG. 11.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

One aspect of the invention is a recognition that deposition of platinumand other noble metals can be substrate dependent under appropriateprocessing conditions. Specifically, it is found that noble metals canbe preferentially deposited on either borophosphosilicate glass (BPSG)or tantalum oxide substrates relative to non-oxidized doped silicon(such as, for example, doped polycrystalline silicon). Further, it isfound that appropriate processing conditions will selectively depositnoble metals on BPSG or tantalum oxide (such as, for example, tantalumpentoxide) relative to aluminum oxide (Al₂O₃). Additionally, it is foundthat appropriate processing can provide a rate of deposition which isselective for various different kinds of oxides and doped non-oxidizedsilicon in the order that the deposition is selective for BPSG relativeto thermally-formed silicon dioxide, and selective for both BPSG andthermally-formed silicon dioxide relative to doped non-oxidized silicon.

Methodologies are described herein for incorporating the selectivity ofdeposition of noble metals on various substrates into semiconductordevice fabrication. For instance, methodologies are described herein forforming capacitor constructions associated with semiconductorsubstrates.

An exemplary process of forming capacitor constructions is describedwith reference to FIGS. 1-5. FIG. 1 shows a fragment 10 of asemiconductor construction at a preliminary processing stage. Fragment10 includes a layer 12 having a layer 14 thereover. Layers 12 and 14 canalternatively be referred to as masses. For purposes of interpretingthis disclosure and the claims that follow, it is to be understood thatthe term “layer” refers to a single, homogeneous or non-homogenouscomposition of material.

Layer 12 can comprise, consist essentially of, or consist of, forexample, an electrically insulative material. An exemplary material forlayer 12 is a composition comprising silicon, oxygen, and at least oneof phosphorous and boron; such as, for example, BPSG or phosphosilicateglass (PSG).

Layer 14 comprises, consists essentially of, or consists of acomposition different from that of layer 12. Specifically, layer 14differs from layer 12 in that a noble metal can ultimately beselectively deposited onto layer 12 relative to layer 14. In particularaspects, layer 14 can comprise doped non-oxidized silicon, thermallygrown silicon dioxide, and/or aluminum oxide. If layer 14 comprisesdoped non-oxidized silicon, it can comprise, for example, at least about1×10₁₈ atoms/cm³ of dopant. The dopant can be either n-type or p-type,and in particular aspects can comprise, consist essentially of, orconsist of phosphorous. The non-oxidized silicon can include one or bothof amorphous and polycrystalline silicon.

Layer 12 is shown supported by a structure 16. Structure 16 cancomprise, for example, a semiconductive material. An exemplarysemiconductive material is single crystal silicon. Structure 16 and/orcombinations of structures 16, 12 and 14 can be referred to as asubstrate, and in particular aspects as a semiconductor substrate. Toaid in interpretation of the claims that follow, the terms“semiconductive substrate” and “semiconductor substrate” are defined tomean any construction comprising semiconductive material, including, butnot limited to, bulk semiconductive materials such as a semiconductivewafer (either alone or in assemblies comprising other materials thereon,such as, for example, conductive and/or semiconductive materials), andsemiconductive material layers (either alone or in assemblies comprisingother materials). The term “substrate” refers to any supportingstructure, including, but not limited to, the semiconductive/conductivesubstrates described above.

It is to be understood that the structure 16 can comprise numerouscomponents and devices (not shown) associated with an integrated circuitconstruction, and formed prior to provision of layers 12 and 14 overstructure 16.

A patterned masking material 18 is formed over layer 14. Maskingmaterial 18 can comprise, for example, photoresist, and can be patternedinto the shown configuration utilizing photolithographic processing.Patterned masking material 18 covers some portions of layer 14, andleaves other portions exposed. Openings 20 extend through maskingmaterial 18 to the exposed portions of layer 14.

In the illustrated aspect of the invention, layer 14 is in directphysical contact with layer 12, and the masking material 18 is in directphysical contact with layer 14. It is to be understood, however, that inother aspects there can be intervening materials between layer 12 andlayer 14, and/or between layer 14 and masking material 18.

Referring to FIG. 2, openings 20 are extended through layer 14 and tolayer 12.

Referring to FIG. 3, openings 20 are extended into layer 12, and maskinglayer 18 (FIG. 2) is removed. It is noted that the extension of openings20 through layer 14 and into layer 12 can be accomplished with 2 or moreseparate etches. Specifically, a first etch can be utilized to extendthe openings through layer 14, and a second etch can be utilized toextend the openings into layer 12. Alternatively, a single etch can beutilized for extending the openings through layer 14 and into layer 12.Also, it is noted that in aspects in which two separate etches areutilized, masking material 18 can be removed after the first etch hasprogressed into or through layer 14, and subsequently the remainder oflayer 14 can be utilized as a mask for extending the openings into layer12.

The construction 10 of FIG. 3 has an outer surface comprising two typesof exposed regions. Specifically, a first region 22 corresponds toexposed portions of layer 12 within openings 20, and a second region 24corresponds to exposed portions of layer 14. The first and secondregions can be considered to be first and second materials,respectively, having different compositions relative to one another.

The first and second regions can comprise any of numerous compositionsin accordance with various aspects of the invention. For instance, thefirst region 22 can comprise silicon oxide (such as, for example,silicon dioxide, PSG and/or BPSG) while the second region 24 comprisesnon-oxidized silicon (which can be, in particular applications, doped toa concentration of at least about 1×10¹⁸ atoms/cm³ with dopant) and/oraluminum oxide.

In other exemplary applications, the first region 22 can comprisetantalum oxide while the second region 24 comprises non-oxidized silicon(which can be, in particular applications, doped to a concentration ofat least about 1×10¹⁸ atoms/cm³ with dopant) and/or aluminum oxide. Inapplications in which the first region 22 comprises tantalum oxide, itcan be preferred to form a thin layer of tantalum oxide (not shown)within openings 20, rather than forming an entirety of layer 12 tocomprise tantalum oxide. Accordingly, layer 12 can comprise BPSG, and athin layer of tantalum oxide can be provided as a liner within theopenings. The liner can comprise, consist essentially of, or consist oftantalum oxide (such as, for example, tantalum pentoxide).

In particular aspects of the invention, first region 22 can comprise,consist essentially of, or consist of a material comprising silicon,oxygen and one or both of boron and phosphorous (such as, for example,BPSG or PSG), and second region 24 can comprise, consist essentially of,or consist of thermally grown oxide. In such embodiments, layer 14 caninitially be provided as non-oxidized silicon, and subsequently can besubjected to thermal processing to convert at least an outer portion ofthe layer to thermally-formed silicon dioxide.

In applications in which material 14 comprises non-oxidized silicon, itis noted that a thin layer of silicon dioxide (typically referred to asa native oxide layer) can form over the non-oxidized silicon if thenon-oxidized silicon is exposed to an oxidizing atmosphere. Accordingly,it can be desired to expose at least a portion of construction 10 tohydrofluoric acid (such as, for example, a solution comprising 100 partswater to about 1 part hydrofluoric acid) to remove native oxide inapplications in which it is desired to have region 24 comprise, consistessentially of, or consist of doped non-oxidized silicon. The exposureto hydrofluoric acid can be accomplished utilizing, for example, ahydrofluoric acid dip, or otherwise rinsing an outer portion ofconstruction 10 with hydrofluoric acid. Suitable removal of native oxidecan be accomplished with a 2 minute dip in hydrofluoric acid at aboutroom temperature.

Referring to FIG. 4, a layer 30 comprising, consisting essentially of,or consisting of at least one noble metal is selectively formed on firstregion 22 relative to second region 24. The at least one noble metal oflayer 30 can be selected from the group consisting of platinum, rhodium,palladium, ruthenium and iridium. For purposes of interpreting thisdisclosure and the claims that follow, it can be useful to distinguishlayers 12, 14 and 30 by referring to layers 12, 14 and 30 as a firstlayer, second layer and third layer, respectively.

The selective formation of layer 30 on first region 22 relative tosecond region 24 can be accomplished by exposing regions 22 and 24 to amixture comprising at least one precursor of the at least one noblemetal in combination with at least one oxidant. Suitable precursorsinclude organometallic precursors of noble metals, such as, for example,methylcyclopentadienyltrimethylplatinum. Suitable oxidants includemolecular oxygen (O₂), nitrous oxide (N₂O), ozone (O₃) and water (H₂O).

Exemplary conditions for formation of layer 30 include a transientnon-equilibrium chemical vapor deposition process in which at least onenoble metal precursor reacts with at least one oxidant to form the layer30. The transient, non-equilibrium, chemical vapor deposition processoccurs in a reaction chamber and differs from a traditional chemicalvapor deposition process in that an equilibrium between the noble metalprecursor and the oxidant is not achieved during the deposition process.

An exemplary process for achieving the non-equilibrium chemical vapordeposition process is as follows. Initially, at least one noble metalprecursor is flowed into the reaction chamber for a time of greater than0 seconds and typically less than or equal to about 5 seconds (forinstance, about 3 seconds). Subsequently, the precursor is partiallypurged from the reaction chamber by flowing one or more non-reactivepurge gases through the chamber for a time of greater than 0 seconds andtypically less than or equal to about 5 seconds. The term “non-reactive”is utilized in referring to the purge gases to indicate that the gasesdo not react with the noble metal precursor or the oxidant. A suitablepurge gas can include, for example, one or both of argon and nitrogen.After the partial purge of the at least one precursor from the reactionchamber, at least one oxidant is flowed into the reaction chamber for atime of greater than 0 seconds and typically less than or equal to about5 seconds (for example, about 2 seconds). Since the one or more noblemetal precursors are only partially purged from the reaction chamberprior to flowing the oxidant into the chamber, there is some mixing ofthe metal precursor(s) with the oxidant during the deposition process.However, the short reaction times are typically not sufficient forequilibrium to develop within the chamber. A suitable temperature withinthe chamber during the non-equilibrium chemical vapor deposition processis from about 100° C. to about 500° C.

A purge step can follow the introduction of oxidant to flush, orpartially flush, the oxidant from the reaction chamber. The purge of theoxidant can utilize a non-reactive purge gas.

While the oxidant and metal precursor(s) are within the chamber, it canbe desired that the level of oxidant within the reaction chamber besufficiently low that reaction between the oxidant and the at least onenoble metal precursor is relatively slow. It is found that if too muchoxidant is provided in the reaction chamber, the selectivity of thedeposition process for layer 22 relative to layer 24 is compromisedand/or gas phase reactions occur which generate particles.

In typical processing, the oxidant utilized comprises, consistsessentially of or consists of one or more of O₂, O₃, H₂O and N₂O. In anexemplary aspect, the oxidant includes a mixture of both O₂ and N₂O,with about 2 parts of N₂O being present for every part of O₂.

The selectivity accomplished utilizing the processing described abovecan be very high. For instance, the selectivity for deposition on aregion consisting essentially of BPSG and/or tantalum oxide relative toa region consisting essentially of non-oxidized silicon and/or aluminumoxide can be at least 9:1, in particular applications at least 99:1, andin some applications the selectivity is so high that there is nodetectable noble metal formed on the second region 24 during theformation of the noble metal on first region 22. The selectivitiesexpressed herein are in terms of the relative thickness of a materialformed over region 22 to the thickness of the material formed overregion 24. Accordingly, a selectivity of at least about 9:1 indicatesthat the material formed over region 22 is at least about 9 timesthicker than the material formed over region 24, (which can includeapplications in which there is no material formed over region 24 duringthe formation of material over region 22). A possible mechanism for theselectivity obtained through processing of the present invention is thatthere is poor nucleation of noble metals with various compositionsrelative to others under the processing conditions. Such mechanism ispresented to assist the reader in understanding the invention, and isnot to limit any claim presented herein unless the mechanism isexpressly recited in the claim.

An atomic layer deposition process can be utilized for selectivelyforming layer 30 on region 22 relative to region 24, rather than thetransient non-equilibrium chemical vapor deposition process describedabove. An atomic layer deposition process would differ from thenon-equilibrium chemical vapor deposition process described above inthat an atomic layer deposition process would utilize complete purgingof the one or more noble metal precursors (or at least substantiallycomplete purging) prior to provision of the oxidant within the reactionchamber. The purging would be complete enough so that there wasnegligible reaction of unutilized noble metal precursor with oxidant inthe chamber. Instead, the at least one noble metal precursor would beutilized without oxidant to form a layer comprising the at least onenoble metal along region 22. In typical atomic layer depositionprocesses, such layer would be a monolayer, or a fraction thereof.Subsequently, residual noble metal precursor would be purged from thereaction chamber, and the layer comprising the at least one noble metalwould be exposed to the oxidant to transform the layer into a desiredcomposition comprising, consisting essentially of, or consisting of theat least one noble metal. The oxidant can then be purged in a mannersimilar to that described above for the purging of the noble metalprecursor. The sequence of forming a monolayer comprising at least onenoble metal and exposing the monolayer to oxidant can be repeatedmultiple times to form composition 30 to a desired thickness.

Referring to FIG. 5, first layer 14 (FIG. 4) is removed and subsequentlya dielectric material 32 and a conductive material 34 are formed acrossan upper region of layer 12 and within openings 20. Layer 14 can beremoved by, for example, chemical-mechanical polishing.

Dielectric material 32 can comprise any of numerous suitable materials,including, for example, silicon dioxide, silicon nitride, aluminumoxide, hafnium oxide and/or tantalum pentoxide. Conductive material 34can comprise conductively-doped silicon and/or various metals.

Conductive material 34 is capacitively coupled with the conductivematerial 30. Accordingly, a pair of capacitor constructions 36 and 38are defined by layers 30, 32 and 34. The capacitor constructions 36 and38 can fall within the general class of capacitor constructions known asmetal insulator metal (MIM) constructions.

Capacitors 36 and 38 can be incorporated into a DRAM array byelectrically coupling the conductive material 30 of each capacitor to abitline (not shown) through a transistor (not shown).

FIG. 6 shows an alternative aspect of the invention relative to that ofFIG. 5. Specifically, FIG. 6 shows construction 10 at a processing stagesubsequent to that of FIG. 4 in an aspect where the layer 14 has notbeen removed prior to formation of dielectric material 32 and conductivematerial 34, and in which layer 14 is not electrically conductive.

FIG. 7 shows construction 10 at a processing step subsequent to that ofFIG. 4 in accordance with another aspect of the invention. The layer 30(FIG. 4) comprising, consisting essentially of, or consisting of atleast one noble metal has been exposed to conditions which cause thelayer to physically roughen. In the shown embodiment, the roughenedlayer 30 consists of a plurality of agglomerates 50. The agglomeratescan be, for example, discrete, substantially spherical masses.

The conditions utilized for roughening layer 30 comprise exposing thelayer to a temperature of at least about 450° C., under an inertatmosphere, for a time of at least about 1 minute. The atmosphere isreferred to as an “inert” atmosphere to indicate that it is non-reactivewith the noble metal of layer 30. A suitable atmosphere can comprise,consist essentially of, or consist of nitrogen (N₂). The temperatureutilized during the roughening can, in particular applications, be atleast about 500° C., and in some applications can be at least about 700°C. The size of the agglomerates 50 can be controlled through control ofvarious processing conditions, including, for example, temperature andexposure time.

In exemplary applications, the layer 30 utilized to form agglomerates 50can comprise, consist essentially of, or consist of a single noble metal(such as, for example, one of platinum, iridium, ruthenium, palladiumand rhodium), and accordingly agglomerates 50 comprise, consistessentially of, or consist of a single noble metal.

Referring to FIG. 8, construction 10 is exposed to suitable etchingconditions for etching into layer 12 while utilizing the agglomerates 50as a mask. The etching forms cavities 52 extending into region 22. In anexemplary application, agglomerates 50 consist essentially of one ormore noble metals, and layer 12 consists essentially of BPSG. Suitableetching conditions can be, for example, substantially selective relativeto layer 14 so that the majority of the layer 14 remains after theetching, as shown.

Referring to FIG. 9, agglomerates 50 (FIG. 8) are removed, andsubsequently a conductive material 54 is formed over layer 12 and withinopenings 20. Conductive material 54 extends into cavities 52, andaccordingly has more surface area than it would in the absence of thecavities. The additional surface area can be beneficial when layer 54 isincorporated into a capacitor construction because such extra surfacearea can increase the capacitance of capacitors formed within openings20 relative to the capacitance of capacitors formed in the absence ofcavities 52.

Although conductive material 54 is shown formed over layer 14, it is tobe understood that the invention includes other aspects (not shown) inwhich layer 14 is removed prior to formation of conductive material 54,and accordingly in which conductive material 54 is formed directly on anupper surface of layer 12. Also, although layer 14 is shown as anelectrically insulative material, it is to be understood that theinvention encompasses applications in which layer 14 is electricallyconductive.

Referring to FIG. 10, layers 14 and 54 are removed from over layer 12,and subsequently a dielectric material 56 and a conductive material 58are formed across layer 12, as well as within openings 20. The removalof layers 14 and 54 from over layer 12 can be accomplished by, forexample, chemical-mechanical polishing. It is noted that although theshown processing removes layer 14, if the layer 14 comprises aninsulative material it can remain. Accordingly, the inventionencompasses other aspects (not shown) wherein layer 54 is removed fromover layer 14 prior to formation of materials 56 and 58, but layer 14remains. Accordingly, materials 56 and 58 can be formed over layer 14.

Dielectric material 56 and conductive material 58 can comprise the samecompositions as discussed above for dielectric material 32 andconductive material 34, respectively, of FIG. 5. Accordingly, conductivematerial 54 can comprise conductively-doped silicon, and/or metal, andthe metal can be in the form of metal nitride and/or in the form ofelemental metal.

Layers 54, 56 and 58 together define a pair of capacitor constructions60 and 62. Such capacitor constructions can be incorporated into a DRAMarray by electrically connecting the layer 54 of each capacitor to atransistor (not shown) which is in turn connected to a bitline (notshown).

FIG. 11 illustrates construction 10 at a processing step subsequent toFIG. 8, in accordance with another aspect of the invention.Specifically, FIG. 11 illustrates conductive material 54 formed overlayer 14 and within openings 20 while agglomerates 50 remain within theopenings. Accordingly, conductive material 54 is provided overagglomerates 50.

FIG. 12 shows construction 10 at a processing stage subsequent to thatof FIG. 11. Specifically, layer 14 has been removed, and layers 56 and58 have been formed over layer 12 and within openings 20. Layers 56 and58 comprise a dielectric material and conductive material, as discussedabove with reference to FIG. 10. The layers 56 and 58 can be consideredto extend into regions 20 contained within layer 12.

A pair of capacitor constructions 70 and 72 are formed from layers 54,56 and 58. The capacitor constructions can be incorporated into DRAM orother memory arrays associated with integrated circuitry. For instance,the capacitor constructions can each be electrically connected to abitline (not shown) through a transistor construction (not shown) toincorporate the capacitors into a DRAM array.

In compliance with the statute, the invention has been described inlanguage more or less specific as to structural and methodical features.It is to be understood, however, that the invention is not limited tothe specific features shown and described, since the means hereindisclosed comprise preferred forms of putting the invention into effect.The invention is, therefore, claimed in any of its forms ormodifications within the proper scope of the appended claimsappropriately interpreted in accordance with the doctrine ofequivalents.

1-116. (canceled)
 117. A semiconductor construction, comprising: amonocrystalline silicon substrate; a silicon-dioxide-comprising materialover the substrate; and spaced islands of noble-metal-containingagglomerates in direct physical contact with thesilicon-dioxide-comprising material.
 118. The semiconductor constructionof claim 117 further comprising: a first conductive layer extending overthe agglomerates; a dielectric layer over the first conductive layer;and a second conductive layer over the dielectric layer; the secondconductive layer being capacitively coupled with the first conductivelayer.
 119. The semiconductor construction of claim 117 wherein thesilicon-dioxide-comprising material includes borophosphosilicate glass.120. The semiconductor construction of claim 117 wherein thenoble-metal-containing agglomerates comprise at least one of Pt, Rh, Ru,Pd and Ir.
 121. A semiconductor construction, comprising: asilicon-containing substrate; an electrically insulative material overthe silicon-containing substrate; noble-metal-containing agglomeratesalong at least a portion of the electrically insulative material;cavities extending into the electrically insulative material between theagglomerates; and a conductive layer extending over the agglomerates andinto the cavities between the agglomerates.
 122. The semiconductorconstruction of claim 121 wherein the conductive layer is a firstconductive layer, and further comprising: a dielectric layer over thefirst conductive layer; and a second conductive layer over thedielectric layer; the second conductive layer being capacitively coupledwith the first conductive layer.
 123. The semiconductor construction ofclaim 121 wherein the noble-metal-containing agglomerates comprise atleast one of Pt, Rh, Ru, Pd and Ir.
 124. The semiconductor constructionof claim 121 wherein the noble-metal-containing agglomerates consistessentially of one or more noble metals.
 125. The semiconductorconstruction of claim 121 wherein the noble-metal-containingagglomerates consist essentially of Pt.